470
FXUS65 KRIW 172145
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
345 PM MDT FRI APR 17 2026
KEY MESSAGES
- SCATTERED SNOW SHOWERS WILL BE POSSIBLE ACROSS MUCH OF THE
STATE THIS AFTERNOON AND EVENING.
- CLEARING SKIES SHOULD ALLOW FOR A HARD FREEZE TONIGHT INTO
SATURDAY MORNING AS TEMPERATURES DROP INTO THE TEENS AND LOW
20S ACROSS NEARLY ALL LOW ELEVATION LOCATIONS.
- DRY AND TRANQUIL WEATHER EXPECTED FROM SATURDAY THROUGH EARLY
NEXT WEEK, WITH ABOVE NORMAL TEMPERATURES RETURNING SUNDAY AND
ESPECIALLY FROM MONDAY THROUGH WEDNESDAY.
UPDATE
ISSUED AT 103 PM MDT FRI APR 17 2026
THE JACKPOT FROM THIS RECENT SYSTEM WAS ACROSS PORTIONS OF
NATRONA AND JOHNSON COUNTIES. SNOW REPORTS FROM THIS MORNING
SHOW AMOUNTS RANGING FROM 3 TO 7 INCHES AROUND CASPER AND 1 TO 3
INCHES ACROSS JOHNSON COUNTY. WHILE FOR THE WIND RIVER BASIN IT
WAS ANOTHER REMINDER OF THE DISAPPOINTMENT THAT WAS THIS
WINTER. LITTLE TO NO SNOW FELL ACROSS THE BASIN, WHICH IS HOW
THINGS WERE TRENDING OVER THE PAST DAY OR SO. AS FOR THE
FORECAST MUCH OF THE PREVIOUS DISCUSSION REMAINS ON TRACK WITH
SCATTERED SNOW SHOWERS DEVELOPING THIS AFTERNOON AND EVENING.
OTHERWISE, THE MAIN FOCUS WILL BE COLD OVERNIGHT TEMPERATURES
FRIDAY NIGHT INTO SATURDAY MORNING. FREEZE WARNINGS REMAIN IN
PLACE ACROSS THE BIGHORN BASIN AND LOWER WIND RIVER BASIN AS
WELL AS THE LANDER FOOTHILLS. TEMPERATURES TONIGHT LOOK TO GET
EVEN COLDER THAN THIS MORNING. CLOUDS CLEARED OUT BRIEFLY THIS
MORNING BUT ARE GRADUALLY BUILDING BACK IN AS A RESULT OF
DEVELOPING SHOWERS. CLOUDS SHOULD CLEAR OUT AFTER SUNSET TONIGHT
LEADING TO MOSTLY CLEAR SKIES OVERNIGHT. THIS SHOULD FURTHER
AID IN THE COOLING, ALLOWING FOR A PROLONGED HARD FREEZE TONIGHT
INTO SATURDAY MORNING ACROSS NEARLY ALL LOW ELEVATION
LOCATIONS. LOWS ARE EXPECTED TO DROP DOWN INTO THE LOW 20S TO
UPPER TEENS EAST OF THE DIVIDE AND LOW TO MID TEENS WEST OF THE
DIVIDE. LOCATIONS SUCH AS YNP MAY SEE TEMPERATURES DROP TO NEAR
OR EVEN POSSIBLY BELOW ZERO DUE TO NEW SNOWCOVER. AS A RESULT,
OF THESE TEMPERATURES FREEZE WARNINGS ARE GOING TO BE ISSUED FOR
PORTIONS OF JOHNSON AND NATRONA COUNTY FOR TONIGHT THROUGH
SATURDAY MORNING. SENSITIVE PLANT LIFE WILL BE IN DANGER ALONG
WITH ANY OUTDOOR PLUMBING SUCH AS SPRINKLER SYSTEMS.
THE REMAINDER OF THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK SEES A
RETURN OF DRY AND MILD CONDITIONS. EARLY SUMMER-LIKE WEATHER ARRIVES
BY MONDAY WITH TEMPERATURES RETURNING TO THE MID TO UPPER 70S EAST
OF THE DIVIDE AND UPPER 60S TO LOW 70S WEST OF THE DIVIDE. BY THE
SECOND HALF OF THE WEEK THERE IS THE POSSIBILITY FOR ANOTHER
DISTURBANCE TO ENTER THE REGION. HOWEVER, ANY HOPES FOR
PRECIPITATION SHOULD BE CHECKED AS THIS MOST RECENT SYSTEM IS A
GREAT EXAMPLE OF HOW QUICKLY THE FORECAST CAN CHANGE. OVERALL,
NEXT WEEK BEARS MONITORING BUT AT THIS TIME, ITS STILL WAY TOO
FAR OUT AND UNCERTAINTY IS TOO HIGH TO HAVE ANY IDEA OF WHAT TO
EXPECT.
DISCUSSION
ISSUED AT 135 AM MDT FRI APR 17 2026
SCORE ONE FOR THE GFS YESTERDAY. IT HAD THE AREA OF SNOW FROM THE
FREMONT / NATRONA COUNTY LINE TO CASPER NAILED DOWN FAIRLY WELL.
SOME SNOW IS CONTINUING THIS MORNING AS I WRITE THIS AROUND 1 AM AND
WILL CONTINUE IN EASTERN PORTIONS OF THE AREA THROUGH THE NIGHT BUT
IT APPEARS THE HEAVIEST SNOW HAS COME TO AN END. WE WILL LIKELY
EXPIRE MOST OF THE ADVISORIES AT 6 AM AND LIKELY CANCEL THE WIND
RIVER RANGE AS MOST GUIDANCE SHOWS THE HEAVY SNOW JUST ABOUT OVER.
WE WILL LEAVE NATRONA COUNTY UP FOR NOW, GIVEN IT HAS BEEN THE
CENTER OF THE HEAVIEST SNOW AND ROADS SHOULD REMAIN SLICK UNTIL THE
STRONG MID APRIL SUN CAN MELT THEM OFF THROUGH THE MORNING.
THE MAIN STORY TODAY WILL BE THE MUCH COLDER TEMPERATURES WHEN
COMPARED THE PREVIOUS SEVERAL DAYS. WITH AREAS THAT SAW SNOW, LIKE
CASPER, STRUGGLING TO GET OUT OF THE 30S. AND, WITH MOIST NORTHWEST
FLOW REMAINING AS WELL AS CYCLONIC CURVATURE OVER THE AREA, THERE
WILL BE SOME CONVECTIVE SNOW SHOWERS AROUND THE AREA AND POSSIBLY A
FEW SNOW BANDS. THESE ARE ALMOST IMPOSSIBLE TO PINPOINT BUT MOST
AREAS WILL HAVE AT LEAST A 1 IN 5 CHANCE OF ONE. ACCUMULATIONS
SHOULD REMAIN LIGHT, WITH A LESS THAN 1 IN 10 CHANCE OF 3 INCHES OR
MORE EVEN IN THE MOUNTAINS, WITH MOST LOCATIONS RECEIVING LESS THAN
AN INCH. AT THIS TIME, TRAVEL CONCERNS FROM THEM SHOULD BE MINIMAL,
AS THE STRONG SUN ANGLE SHOULD KEEP ROADS MAINLY WET UNLESS THE SNOW
PERSISTS.
THESE SNOW SHOWERS SHOULD DECREASE AS WE LOSE THE HEATING OF THE
DAY, WITH MOST ENDING BY MIDNIGHT. THE CONCERN THEN TURNS TO THE
COLD TEMPERATURES. WE STILL LOOK TO HAVE A WIDESPREAD FREEZE ACROSS
MANY LOCATIONS EAST OF THE DIVIDE. WE WILL CONTINUE THE FREEZE
WARNINGS IN THE ZONES THAT ALREADY HAVE THEM. WE WILL LIKELY NEED
THEM IN OTHER ZONES BUT WILL LET THE DAY SHIFT DO THAT AFTER THE
WINTER WEATHER ADVISORIES ARE OVER. EXPECTED LOW TEMPERATURES HAVE
COME UP A BIT IN THE AREA WITH LITTLE SNOW, BUT MOST LOCATIONS STILL
HAVE A GREATER THAN 4 OUT OF 5 CHANCE OF LOW TEMPERATURES BELOW 25
DEGREES. EXACTLY HOW COLD IT DOES GET WILL HAVE TO DO WITH HOW
QUICKLY THE SKY CAN CLEAR, AND THERE IS STILL SOME UNCERTAINTY WITH
THIS.
MORE TRANQUIL WEATHER SHOULD THEN BE THE RULE FOR AT LEAST THE NEXT
4 DAYS AS RIDGING BUILDS ACROSS THE NORTHERN ROCKIES. TEMPERATURES
WILL BEGIN TO REBOUND. SATURDAY LOOKS NEAR TO BELOW NORMAL, BUT THEN
MUCH WARMER TEMPERATURES MOVE IN FOR SUNDAY AND THROUGH AT LEAST
WEDNESDAY. MONDAY AND TUESDAY LOOK ESPECIALLY WARM, WITH SOME OF THE
WARMER SPOTS MAKING A RUN AT 80 DEGREE HIGH TEMPERATURES. THE ONLY
CONCERN WOULD BE POSSIBLE ELEVATED FIRE WEATHER, ESPECIALLY IN AREAS
FAVORED TO SOUTHWESTERLY BREEZES, LIKE CASPER. SATURDAY LIKELY WON'T
BE A PROBLEM WITH THE SNOW BRINGING SOME NEEDED MOISTURE, BUT
POSSIBLE SUNDAY AND EARLY INTO NEXT WEEK, ESPECIALLY WEDNESDAY. THE
NEXT POTENTIAL WEATHER MAKER IS AN UPPER LEVEL LOW THAT WILL MOVE
INTO THE PACIFIC NORTHWEST ON TUESDAY AND MOVE TOWARD THE AREA FOR
THE MIDDLE OF THE WEEK. THERE HAS BEEN POOR MODEL CONSISTENCY IN
REGARDING THE LOW, SO DETAILS ARE IMPOSSIBLE TO PREDICT AT THIS
TIME. HOWEVER, THIS LOOKS TO BE OUR NEXT CHANCE OF PRECIPITATION FOR
THE MIDDLE OR END OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 345 PM MDT FRI APR 17 2026
VFR CONDITIONS EXPECTED AT ALL LOCATIONS THROUGHOUT THE ENTIRETY
OF THE PERIOD. WINDS WILL DIMINISH BY 02Z WITH RADIATIONAL
COOLING AND IMPROVING SKIES OVERNIGHT. WITH THAT, EXPECT A LIGHT
FOG POSSIBLE (20-30%) AROUND CPR WITH THE RECENT SNOWFALL.
OTHERWISE, A LOW SCATTERED STRATUS DECK AROUND JAC OFF THE LAKE
BUT OTHERWISE VFR EXPECTED. WINDS WILL INCREASE ONCE AGAIN
TOWARDS 16-17Z WITH DAYTIME HEATING AND MIXING TO THE SURFACE,
HIGHEST AT CPR/RKS UP TO 25KTS AND UP TO 18KTS AT COD/RIW. THIS
WILL LAST THROUGH THE END OF THE PERIOD WITH NO OTHER WEATHER
ELEMENTS EXPECTED AT THIS TIME.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
FREEZE WARNING UNTIL 9 AM MDT SATURDAY FOR WYZ003>006-017-018.
FREEZE WARNING UNTIL 9 AM MDT SATURDAY FOR WYZ010-011-019-020.
UPDATE...DZIEWALTOWSKI
DISCUSSION...HATTINGS
AVIATION...LOWE
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